Mobile submarine simulator

The mobile submarine simulator (MOSS) is a sonar decoy used by submarines of the United States Navy. It is a 21-inch torpedo, without an explosive warhead, but able to generate a strong sound signature recorded to be extremely similar to that of the launching submarine.

The MOSS first entered service in 1976 and has been deployed on all American ballistic missile submarines since the 1980s. It has been progressively improved through its service life; an extended-range variant is known as the LEMOSS -- the long-endurance mobile submarine simulator.